My views, opinions and reviews of CAD, PLM and the Product Development Process.

Monday, May 18, 2009

Model Based Definition (MBD) – What’s the Hold-Up?

Recently I have been talking with several companies about the possibility of reducing their dependency on fully detailed drawings. In a recent post titled “The Maturity Curve of Product Development” I used the following chart to show the different stages that companies go through as they learn to leverage their electronic CAD data deeper and broader into the product development process.

Model Based Definition (MBD) is a term used to describe the addition of information to the 3D model such that the model can represent the complete definition of parts and assemblies. For most companies, this complete definition is usually developed and managed in the 2D drawing and other related documents. At its fullest extent, model based definition can make it possible to reduce and even eliminate the need for 2D drawings.
Recently, Matt Lombard at Dezignstuff.com asked if any of his readers were using the 3D CAD Standards that are laid out in the ASME Y14.41 standard. This standard basically defines how 3D models are to be documented and annotated to fully represent the complete definition. So far he has not received too many responses, and no response that indicates the use of this standard and MBD.
Much time goes into creating fully detailed drawings. They can be expensive to create and manage. They can be easily misinterpreted. If developed from a 3D model, there is much duplication of effort. With duplication of effort comes a higher potential for error. Drawings can quickly become detached or unrelated to the 3D model. Once printed, they can become even more detached from the 3D model, and the opportunity for error increases. So, what’s the holdup?

Example from ASME Y14.41

Same part annotated in CoCreate Modeling

I have read a few success stories about MBD, but I have yet to witness one. As engineers at Hewlett Packard, we were successful with reduced content drawings, but we never made it to a “drawing-less”, or MBD process. There have been many claims to successful MBD in aerospace, automotive, and high tech electronics. I have visited many of these companies and am still looking for some good examples. I have seen some small examples from some progressive individuals or even small groups that have been able to push forward with MBD to some extent, but nothing that encompasses the complete product lifecycle. Maybe I just haven’t visited the right places.
What does it take to move to a model based definition? The technology exists. Most all modern 3D CAD tools have some capability for MBD. Some are better than others. Several free viewers are also available to read and view these annotated parts and assemblies. I would love to hear from some of the readers. What are the challenges you would face, or are facing?

Same part viewed in eDrawings

Same part viewed in 3D PDF

As I stated in the post regarding the maturity curve, making the move up the curve will be an evolutionary move – one step at a time. First, you need to understand where, when and why part and assembly definitions exist in printed form. I see a significant use of computers on the shop floor, in manufacturing and assembly. It’s even becoming common to see 3D representations of parts and assemblies on the monitors. But it’s equally common to see a printed 2D drawing lying on the workbench next to the monitor.
As we continue to move to 3D based product design and manufacturing, the development and management of drawings will become a duplication of resources and effort, effort that we may not be able to afford much longer.
Here are some challenges to MBD that people have shared with me.

The culture chasm, it’s a giant leap

Quality management/inspection

Compliance with industry specific regulations

Our suppliers, partners

Cost & disruption vs. value

Inadequate tools/technology

I recently needed to make a part on the lathe in my garage that I first designed in 3D. I didn’t take my laptop with me; I took a printed drawing – hum…

Paul

I recently published another article on MBD that can be found here. It perhaps provides a more broad perspective on what MBD can be.

22 comments:

Anonymous
said...

Working for HP, we documented mechanical designs using 3D models and supplemental 2D drawings back in the early 90's. I've investigated all sorts of ways to embed what's left on the 2D drawing into the model. There's lots of issues that prevent you from doing this, some which you describe. One reason is that drawings actually work quite well. The reason we're still using them is that they've proven to be effective for capturing design intent. As long as there are people involved in the process, we're going to need drawings. We've actually progressed quite far in embedding design intent in the 3D model. If you want a comparison, look at the design files that Mentor spits out for pca design. Now there's an opportunity for improvement :-).

Any information that is currently on a 2D drawing will need to be stored in the 3D Model for this to happen. It's not like you don't have to do the work just because you no longer have a 2D drawing anymore. If anything, the amount of work increases because the detail no longer relies on drawing shorthand avaiable in Y14.5. Besides that, the standards for MBD are still in the stone ages.

I love the idea of MBD, however my attempt in Solidworks have often turned into what looks like a big mess, and I have only got negative feedback from people when I have handed down models with MBD.Mastercam do not recognize Solidwork imports with MBD what kinda destroys the idea of eliminating the old fashion prints to the floor(not sure who's fault that is). Actually MBD for Mastercam is a add on from Verisurf I believe and is about $1000.

Thanks for the responses so far. From these responses we can add the following to the list of challenges or answers to “What’s the holdup?”

- There is much other data that is conveyed on the drawing and not easy to do in 3D- Drawings actually work quite well- Level of effort may be higher in 3D than in 2D- ASME Y14.41 may not be adequate- The tools to create and consume MBD may not be adequate

Thank you for adding the ASME Y14.41 standard into the MBD conundrum. The lack of standards available to designers to effectively reduce their design efforts while including MBD criteria are non-existent. Is there a quick reference guide available outside of a company's proprietary documentation that covers good modeling techniques that include MBD criteria?

I have not seen any evidence of a good reference guide for the application of MBD.

I think one of the challenges to developing a "guide" or "best practices" is the fact that each CAD system today provides different capabilities and methods for MBD. These differences extend to how this data can be transferred and utilized in different systems.

There is also much more to MBD than Y14.41. We should take a close look at all of the information that is typically found on a drawing. Where does all of this information come from? And how can we collect it all in the context of a 3D model - in a way that can be utilized in downstream processes.

I was a tool & moldmaker/machinist for 16 years with PA journeyman's degree. I have been machine designer for the last 15 years. I do not see the MBD becoming a reality fo a long time. In addition to the prior posts, the data would need to be highly portable and provide the visiblity/clarity of an "E" sized drawing. What devise can do this? A Kindle is far away....

I am seeing more and more machinists using computers with large high-resolution monitors today. It can be much better than paper as you can clean the monitor without messing up the drawing. You also don't need a magnifying glass to see small detail, just zoom in. You can also shade the image for clarity, no more colored pencils. You can also rotate the image for any view you want, no more missing views. You can also filter for what kind of information you are looking for to avoid the clutter.

Your point about "data being highly portable" is a very valid point. Considering all the data that is represented in a typical mechanical drawing, there is certainly more to “definition” than geometry, dimensions and tolerance. Technically though, there is no reason this “other” information cannot be accessed through HTML tags attached to the 3D model. For some companies this “other” information, like change notes for example, is all ready in the PDM system. These extra tags just need to be made available in an industry standard format, AND it needs to be easier and faster than drawings.

I like your comments on MBD and would like to try to implement this in some aspects of our shop detail drawings. We currently generate 2D PDF drawings and it looks like the MBD can be made to have the same information.

I believe the best approach is to embed the MBD into a 2D PDF drawing. That way we can use our standard 2D titlebox, supplementary 2D sketches and bill of material while giving the customer the ability to use the capabilities of 3D PDF.

The benefit of the MBD is that it has sufficent information to drive CNC equipment and survey equipment such as the FARO. This should limit the amount of 2D information we need to show for fabrication while providing the customer with the data needed to drive their fabrication equipment.

Since the 2D print of the MBD can be made to have the same information as the 2D drawing, there should be no loss of information in using a print of the MBD as opposed to using a standard 2D drawing. Some may even find a print of a MBD easier to read than a standard 2D drawing.

Thus far I have been unable to get the 3D annotations, like dimensions, in my ".pkg" files to convert over into the 3D PDF. From your example it looks like you were able to do this. I would like to find out how this is done.

Anonymous,Implementing MBD will be best done through a phased approach. Understanding who the "consumers" are of engineering data and what their requirements are is one of the first steps. A consumer might be the NC programmer, tooling, assembly, inspection, and many others. Some of these might be in house and others are external. Find out who they are, what they are trying to do with the data and what they are looking for in the data. Then start mapping those requirements back to MBD requirements and needed capabilities. 3DPDF is certainly one of the tools that must be considered. Inspection may likely be the most challenging area, and if you are required to create fully detailed drawings just for inspection, it's difficult to take additional effort in developing fully annotated models as well. There may be some duplication of effort during the transition. Many CAD systems - at least I know CoCreate - will display all the 3D annotation directly on the drawing, so when a drawing is required there is very little effort in creating it.

Culture, habits, data management practices and the general process of change will all play a role, but with a little discipline and management support, it can be done. Let us know how your project goes - challenges and successes.

I found that my ProE WF5 counterpart cannot share MBD with me. We were hoping for step or WF import to eliminate the need for 2D sheets which do not transfer. Only another Wildfire will reveal the model based definition data.

John, Have you tried eDrawings or 3D PDF? These formats should work fine. Or perhaps you need fully editable geometry and prefer STEP. Perhaps you will need to get geometry through STEP and MBD through eDrawings.

I'm not sure how well STEP handles MBD attributes and data. I know AP203 will support 3D notes, but I don't know how well STEP, in general, supports MBD. I'll do some checking, and perhaps another reader can contribute as well.

I used to teach CATIA V5 at the National Institute for Aviation Research at Wichita State University in Wichita, KS. When I taught employees at Spirit Aerosystems, they were implementing MBD due to the 787 program from Boeing. Their method was to place low-end viewers on the shop floor where employees could see the 3D content and the annotations. MFG engineers would generate step by step captures in CATIA that would allow them to orient and highlight areas on the parts for adhesives, installation of fasteners, etc. I would teach shop floor personnel with limited computer experience how to look at these models in order to do their jobs. As far as inspection, your best bet is to utilize the software packages designed to integrate with each other. Unfortunately this can be costly, but it is still a solution. If you have Mastercam X4 or X5, it reads CATIA V5 MBD directly. Unfortunately where I currently work, we still use PowerInspect for some Romer arms that only reads IGES. Therefore...no MBD. I'm looking into conversion software that translates the associative text into polylines, but it still loses associativity in IGES, therefore, my CMM operators/programmers still have to refer to the original MBD dataset to ensure that features are linked to the same tolerance.

Hi Paul, I work for a very large defense contractor. We are working towards MBD. The challenges we face are far more complicated than authoring data in the 3D model. While there are still some short comings with our modeling software, we are also faced with many downstream processes that are very old in the PLM. The processes dont die easy and replacing them is very expensive. I believe the "hold up" is a combination of issues. I can not see many smaller companies having the capital to make such a paradigm shift very easily. Granted, the smaller the company, less are the issues. The larger players will have a lot to address.

Anonymous,Thanks for the comments. I agree, the biggest challenges are not related to developing the 3D model and annotation. I have been visiting many companies that have an interest in reducing the investment in drawing creation and management, but due to culture, habits, process and in some cases a push back in the supply chain, it is difficult to make progress. I am trying to understand the ROI on a successful MBD initiative. I assume there is an ROI based on the fact that some companies have made it work, but what is the return? Do we really understand the cost and the value yet?

MBD will be the way of the future for engineering as it has already begun. My organization has over 50 years of historical data that includes manual draiwngs that are still the system of record.The change to MBD has begun but needs to be taken in calculated steps. During a MBD pilot program we found the basic problem is that engineering is good to go with MBD but all post-engioneering processes are based on a 2D draiwng system. Changes have begun to change that and new tests will be performed.Keep up the fight!

About Me

I have been involved in product development, manufacturing and CAD/CAM/PLM for over 30 years. My primary interest has been in 3D CAD, specifically Direct Modeling.
My postings on this site are my own and don't necessarily represent the opinions, positions and strategies of my employer or any other company.